Preparation of olefin lubricant having a high viscosity



Patented Nov. 4, 1952 PREPARATION OLEFIN LUBRICANT HAVING A HIGHVISCOSITY Raymond L. Heinrich, Baytown, Tex., assignor,

by mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation of Delaware.

N Drawing. Application December 6, 1950, Serial No. 199,571

. r 4 Claims. (01. 2so 451 The present invention is directed toa-lubricating oil composition. More particularly, the invention isdirected to a method of preparing a lubricating oil composition having ahigh viscosity and a low neutralization value. In accordance with thepresent invention a high viscosity lubricating oil composition having alow neutralization value is prepared by forming a mixture of an olefiniclubricating oil polymer having lubricating oil characteristics and anamount in the range between 0.1% and 5% by weight of diphenylthioureatThe mixture is then subjected to oxidizingconditions at an elevatedtemperature for a time sufiicient to form an oxidized product. Theoxidized product is appreciated in viscosity by formation of oxidizedbodies but the oxidized product has a relatively low neutralizationvalue indicating that the oxidized bodies are not acidic in nature.

The diphenylthiourea employed in the practice of the present inventionmay be used, as stated, in an amount in the range between 0.1% and 5% byweight with a preferred range from 0.5% to 3% by weight. An amount whichgives very satisfactory results is 1% by weight.

The olefinic lubricatingv oil polymer employed in the practice of thepresent invention may be obtained by polymerizing. alpha olefins toproduce polymers in the lubricating oil boiling range and havinglubricating oil characteristics. Such polymers may be produced bypolymerizing alpha olefins boiling in the range between 100 and 400 F.in the presence of a Friedel -Crafts catalyst at a temperature of aboutto 200 F. Olefins which may be polymerized to produce lubricating oilpolymers are the alpha olefins having from 5 to 10 carbon atoms in themolecule including pentene-l, hexene-l, heptene-l, octene-l, nonene-l,and decene-l. A convenient source of alpha olefins is the naphthafraction produced in the Fischer-Tropsch synthesis when employing apromoted iron catalyst. The olefinic lubricating oil polymer willordinarily be employed in an amount in the range between and 99.9% byweight with a preferred range being from 97% to 99.5% by weight.

In oxidizing a mixture of olefinic lubricating oil polymer havinglubricating oil characteristics and diphenylthiourea, the mixture may beoxidized at a temperature in the range from 300 to 600 F. The oxidationtime may range from about 30 minutes up to about 16 hours. Air is asuitable source of oxygen but other sources may be used.

In order to illustrate the invention further, a number of compositionswere made up in which various additives were admixed with an olefinicTable Oxidation Promoter Tests on Oxidized Oils Olefin Polymer i Wt.Percent Prometer Percent Increase Vis., sludge Formation Neut. ValueNone Beta-Naphthol Diethanol Sulfide Hydroquinone. Hydroquinone Dibenzylp-Amino P Sulfur Monochloride...

fi-Toluene Sultonyl Amide.

enzene Sultonyl Amide None. D

0. Moderate. None.

1 Prepared by A101; catalyzed polymerization of octane-l, 47.7 vis., 210F. SS0, viscosity index. 1 Extremely viscous material, too viscous forSSU viscosity determination.

0'. Very Heavy It will be seen from the foregoing results that of 10additives added to the olefinic polymer only diphenylthiourea increasedthe viscosity while yet maintaining a low neutralization value. Highneutralization values are indicative of high acid contents which areundesirable in lubricating oil. These data show that the viscosity of anolefinic polymer may be varied by varying the amount of the diphenylthiourea to produce nearly any desired viscosity While yet allowing theproduction of a lubricating oil having a low neutralization value and inwhich is not formed any substantial amount of sludge. d

The oxidation of the naphthenic mineral oil in the method of the presentinvention was carflask is 5 cm. long and has an inside diameter of a 3cm. The flask has two opposed side necks which are 6 cm. long and 1.5cm. inside diameter, and are situated at a 30 angle with the centralneck, perpendicular to the surface of the spherical flask. The stirreris a glass rod 0.5 cm. in diameter, entering the flask through a glasstube bearing held in place by a rubber stopper in the central neck, withtwo glass blades 1.0 cm. long by 0.7 cm. wide welded to opposite sidesof the bottom end of the glass rod at a 30 angle with the vertical. Thestirrer is driven by a 1750 R. P. M. motor connected to the stirrer by arubber tubing coupling. The blades of the stirrer are situated about 0.5cm. from the bottom of the flask and spin in such a direction that theirpropeller-like action circulates the oil to the bottom of the flask, upalong the sides of the flask, back to the center of the flask, and downto the stirrer blades again. A considerable amount of air is sucked downwith the descending oil and intimately contacted with it by the actionof the stirrer. A thermometer well 5cm. long and 1.0 cm. inside diameteris situated in one side of the flask equidistant from the two side arms.During the oxidation the flask is about twothirds immersed in an oilbath maintained at 375 F. The temperature of the oil in the flask isusually 5 to 10 F. below the temperature of the oil bath.

The oxidation operation is carried out in the specially constructedflask by stirring 100 cc. of the sample in the presence of air forsixteen hours at 375 F. At the end of that time the flask is removedfrom the oil bath and tests obtained on the oxidized oil.

While the oxidation operation was carried out for 16 hours at 375 F.,the operation to appreciate the viscosity may be conducted at a lowertemperature for a longer period of time or at a higher temperature for ashorter period of time. For example, the oxidation may be carried out ata temperature in the range from 300 to 600 F. and for a time rangingfrom about 30 minutes up to 16 hours.

The neutralization value which is used as a method of test is describedin A. S. T. M. Stand-' While the neutralization value of the oxidizedproduct in accordance with the present invention is low it may bedesirable to decrease the neutralization value even further. This may bedone by contacting the oxidized product with an adsorbent material, suchas a contact clay. Another way of lowering the neutralization value isto neutralize the organic acidic material with an alkaline material,such as a solution of sodium hydroxide or sodium carbonate.

The oxidized product of the present invention may suitably be used as acompounding oil and may find particular usage as a component of steamcylinder lubricant or as the hydrocarbon component in greasemanufacture.

The nature and objects of the present invention having beencompletely'described and illustrated, what I wish to claim as new anduseful and to secure by Letters Patent is:

1. A method for increasing the viscosity of an ing oil characteristicswhich comprises oxidizing olefinic lubricating oil polymer havinglubricatthe polymer at a temperature in the range from 300 to 600 F. inthe presence of a promotional amount no less than 0.1% by weight ofdiphenylthiourea to form an oxidized product having an increasedviscosity and a low neutralization value and recovering said product.

2. A method for forming a high viscosity lubricating oil which comprisesforming a mixture of a lubricating oil polymer of an alpha olefin havingfrom 5 to 10 carbon atoms in the molecule and a promotional amount noless than 0.1% by weight of diphenylthiourea, oxidizing the mixture at atemperature in the range from 300 to 600 F. to form an oxidized producthaving an increased viscosity and a low neutralization value andrecovering said product.

3. A method for forming a high viscosity lubricating oil which comprisesforming a mixture of a lubricating oil polymer of octene-l havinglubricating oil characteristics and 1% by weight of diphenylthiourea,oxidizing the mixture at a temperature of about 375 F. for a timesufficient to form. an oxidized product having an increased viscosityand a low neutralization value and recovering said product.

4. A method for producing a high viscosity lubricating oil whichcomprises forming a mixture of a lubricating oil polymer of an alphaolefin having from 5 to 10 carbon atoms in the molecule and apromotional amount in the range from 0.1% to 5% by Weight ofdiphenylthiourea, oxidizing the mixture in the presence of air at atemperature in the range from 300 to 600 F. for

a time in the range from. 30 minutes to 16 hours to form an oxidizedproduct having an increased viscosity and a low neutralization value,and recovering said product.

RAYMOND L. HEINRICH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

1. A METHOD FOR INCREASING THE VISCOSITY OF AN ING OIL CHARACTERISTICSWHICH COMPRISES OXIDIZING OLEFINIC LUBRICATING OIL POLYMER HAVINGLUBRICATTHE POLYMER AT A TEMPERATURE IN THE RANGE FROM 300* TO 600* F.IN THE PRESENCE OF A PROMOTIONAL AMOUNT NO LESS THAN 0.1% BY WEIGHT OFDIPHENYLTHIOUREA TO FORM AN OXIDIZED PRODUCT HAVING AN INCREASEDVISCOSITY AND A LOW NEUTRALIZATION VALUE AND RECOVERY SAID PRODUCT.